Additional formal logic concepts and common informal logical fallacies with a short example of each, set II.
35 cards · basic cards · AI-written, checked twice. Edit anything.
- What is De Morgan's first law?
Show answer
The negation of a conjunction is the disjunction of the negations: not(A and B) = (not A) or (not B).- What is De Morgan's second law?
Show answer
The negation of a disjunction is the conjunction of the negations: not(A or B) = (not A) and (not B).- What is the contrapositive of a conditional, and is it logically equivalent to the original?
Show answer
The contrapositive of 'if A then B' is 'if not B then not A'. A conditional and its contrapositive are logically equivalent.- What is a biconditional statement?
Show answer
A statement 'A if and only if B' that is true when A and B have the same truth value, both true or both false.- What is a vacuous truth?
Show answer
A conditional 'if A then B' is vacuously true when the antecedent A is false, regardless of whether B is true or false.- What is a contradiction?
Show answer
A proposition that is false under all possible truth value assignments to its variables.- What is a contingent proposition?
Show answer
A proposition that is true under some truth assignments and false under others, neither a tautology nor a contradiction.- What is the fallacy of affirming the consequent?
Show answer
Arguing from 'if A then B' and 'B is true' to conclude 'therefore A is true', which does not follow logically.- What is the fallacy of denying the antecedent?
Show answer
Arguing from 'if A then B' and 'A is false' to conclude 'therefore B is false', which does not follow logically.- What is a disjunctive syllogism?
Show answer
A valid argument form: from 'A or B' and 'not A', you can validly conclude 'B'.- What is a hypothetical syllogism?
Show answer
A valid argument form: from 'if A then B' and 'if B then C', you can validly conclude 'if A then C'.- What is a material conditional?
Show answer
A conditional 'if A then B' that is false only when A is true and B is false; true in all other cases.- What is an ad hominem fallacy?
Show answer
Attacking the person making an argument rather than addressing the argument itself, as if a character flaw refutes the claim.- Give an example of an ad hominem fallacy.
Show answer
'You cannot argue for gun control because you are a politician' instead of examining their actual reasons.- What is a straw man fallacy?
Show answer
Misrepresenting an opponent's argument in a weaker or more extreme form, then attacking that exaggerated version instead of the actual argument.
FlashKeepers